Treatment of paper or textile fabrics



Patented Aug. 27, 1946 FABRI William Charlton, Stanley Graham Jarrett, and Eric Everard Walker, Blackley, Manchester, England, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing. Application March a, 1944, Serial This invention relates to a treatment of paper or textile fabrics and more particularly to new methods of finishing such materials.

In the specification of British application No. 11,780/42 there is described'a method of subjecting materials consisting of or containing wool fibres at elevated temperatures to the combined action of water-vapour and'the vapour of a volatile monomeric monovinylidene compound, for example, an ester of acrylic Or methacrylic acid. styrene or a vinyl ester.

According to the present invention we provide a process for treating paper or textile fabrics which comprise exposing said materials to the vapour of one or more monomeric readily polymerisable compounds in the presence of persulphuric acid or a water-soluble persulphat and in the presence of a water-soluble oxy-acid of sulphur with reducing properties or a watersoluble salt of an oxy-acid of sulphur with reducing roperties.

The paper may be of any kind within the common meaning of the term. The textile fabrics may be woven or knitted and composed of fibres which may be animal or vegetable, for example wool, cotton or jute; or of vegetable origin, for

example viscose r acetate rayon; or entirely synthetic, for example synthetic linear polyamide (nylon) fibres; or mixtures of such fibres.

The monomeric readily polymerisable compounds are those containing the group CH2= C: and they include, for example, acrylic acid, methacrylic acid, esters of acrylic acid, esters of methacrylic acid, acrylonitrile, vinyl esters, vinyl ethers and styrene. Of these, the lower alkyl or alkylene ester of acrylic acid and of methacrylic acid, for example, methyl and ethyl acrylates and methacrylates, are especially suitable; the higher alkyl esters (wherein th alkyl group has more than 6 carbon atoms), for example, Z-ethylhexyl methacrylate and octadecyl methacrylate, are less suitable since they polymerise more slowly or to a lesser extent under the conditions employed. B-Ethoxyethyl methacrylate and n-butyl methacrylate are also very suitable, the former being the more easily polymerised, due probably to its greater solubility in water caused by the presence of the ether grouping. Unsaturated esters such as diallyl maleate are also suitable. Vinyl esters, particularly the inorganic esters, are les suitable since they polymerise very slowly under the conditions employed. In general, the monomeric readily polymerisable compounds used should have high vapour pressures at temperatures below 7 100 0., so as to obviate the need for using tem- 55 acid, sulphur dioxide in admixture with water In Great Britain February 15,

8 Claims. (Cl. 117-1395) peratures substantially higher than 100 C.for

vapourising substantial proportions of said compounds; heating at temperatures above,l00 C. is not desirable, since such heating tends to dry off the fabric and to destroy the efficacy of polymerisation catalyst and activator.

The exposure of the paper or fabric to the monomeric polymerisable compounds under the conditions herein described. causes these compounds to be polymerised on the paper or fabric in a much shorter time than has hitherto been found possible. Frequently, it has been found that deposition'of the polymers can be effected rapidly at temperatures as low as C. or even lower, although, with some monomers, working the paper or fabric to be moist with water; if the paper or fabric isdry, polymerisation is extremely slow. A 2% solution of ammonium persulphate, used so that the amounts of solution retained by the fabric or paper are from one to two times the weight of th fabric or paper, has been found to give satisfactory results. Weaker solutions, for

example 0.5%, may be used if desired.

The exposure to the vapour of the monomers is conveniently carried out by entraining the vapour in an oxygen-free gas, such as carbon dioxide or nitrogen and then int'erposing the paper or fabric in a stream of the gas and vapour. Inert volatile liquids such as water or an alcohol may be mixed with the compound'being vapour- -ised. Theexposure may beat atmospheric or elevated temperatures.

Examples of suitable water-soluble salts of oxyacid of sulphur with reducing properties are sulphites, hydrosulphites, sulphoxylates, pyrosulphites, bisulphites, and thiosulphates, in particular the sodium salts. These are conveniently applied to the paper or fabric, as by soaking in or impregnating with dilute aqueous solution thereof, and they are usually used in amounts less than the amounts of the persulphuric acid or water-soluble persulphate used. Alternatively, when using a free acid, forinstance .sulphurous vapour may be entrained with th vapour of the monomer in a carrier gas. Or, gaseous sulphur dioxide in admixture wtih a carrier gas may be passed through the paper or fabric which is moist with water.

The effects produced varywith the nature of the paper or' the fabric, the monomer and the amount of polymer deposited, and may be modifled by using more than one monomer. When using more than one monomer, it is sometimes advantageous to use a mixture comprising both slow the-followin examples, in which, unless otherwise stated, the parts are expressed by weight:

Ezample 1 Cotton fabric is impregnated with a cold solution of ammonium persulphate (1 part) and sodium hydrosulphite (0.5 part) in water (98.5 parts), and excess of the solution removed by squeezing or passing between rollers. The fabric is suspended in the upper part'of a cylindrical vessel in the bottom of which is placed methyl acrylate in excess of th amount to be polymerised on the fabric. through the methyl acrylate, and the vessel is heated in a water bath at 40-60 C. for as long as required. Depending on the rateof flow of carbon dioxide, the temperature of 'the vessel, the relative weights of monomer and fabric, and the time varying amounts of monomer are deposited and polymerised on the fabric. For instance a gain in weight of 80% of the fabric weight is obtained in about 30 minutes. When suflicient polymer is formed on the fabric, it is rinsed in warm water and dried,

Depending on the amount of polymer formed on the fabric, different efiects are produced. Thus the deposition of a small amount of polymer gives a soft handle, whereas a large amount gives a fabric resembling oiled-silk in appearance.

Example 2 A stream of carbon dioxide is bubbled successively through a saturated solution of sulphur dioxide in water at 20 0., then through methyl methacrylate at 25 C., a si'ntered glass distributor being used to give a good contact between gas and monomer. The carbon dioxide, which carries entrained with it small amounts of methyl methacrylate and sulphur dioxide is passed upwards through a shallow horizontal chamber kept at 20-25 C. Cotton fabric which has previously been impregnated with a dilute solution of 2 parts Carbon dioxide is bubbled chamber is at about 0., vinyl acetate polymer is formed to the extent of about 7% of the fabric weight during 2 hours.

Under similar conditions, but with the monomer maintained at 100 C., diallyl maleate polymer is formed to the extent of about 43% of the fabric weight during 2 hours.

Exampl 3 Methyl methacrylate is caused to polymerise in the manner described in Example 2 on fabrics composed of viscose rayon and of polyhexamethylene adipamide (nylon) yarn, respectively. Polymerisation is continued until an increase in weight of 18% is obtained in the case of the viscose rayon fabric and until an increase in weight of 25-30% is obtained in the case of the polyhexamethylene adipamide fabric. In bothcases the fabrics are delustred by the treatment.

Example 4 .Acrylonitrile is caused to polymerise on 9. variety of fabrics in the manner described in Example 2. At temperatures of 20-25 C., the followin amounts of acrylonitrile polymer are deposited in the timesstated:

On cotton fabric 55% by weight of the cloth in 45 minutes.

On viscose rayon fabiic 25% by weight of the cloth in 45 minutes.

0n woollen fabric 10% by weight of the cloth in 35 minutes.

'The cotton fabric is stiffened, the viscose rayon fabric is stiffened and delustred by the treatment, and the woollen fabri has a fuller handle. The

effects are not destroyed by boiling the fabrics in aqueous 5% soap and the 1% soda solutions, but a yellow colour develops.

Example 5 the solution, is placed in the chamber so that the' gas stream passes through it. The rate of passage of the carbon dioxide is 4.3 gms./sq. cm. of fabric/hr; After 30 minutes treatment methyl acrylate polymer is formed on the fabric to the extent of 93% of the fabric weight.

on the fabric, it is removed, washed with water,

, and dried.

If the flow of carbon dioxide is increased to 8.6 ems/sq. cm. of fabric/hr. the amount of polymer formed in the same time falls to 74% of the fabric weight.

Example 6 The recipe of Example 5 is employed to form p-ethoxyethyl methacrylate polymer on a cotton fabric. At a rate of flow of carbon dioxide of 2.15 gms./sq. cm. of fabric/hr the amount of 'polymer formed on the'fabric in 30 minutes is 10.5% of the fabric weight. When the temperature ofthe p-ethoxyethyl methacrylate is increased to 50 C. or 75 C. the amounts of polymer deposited in the same time are 23% and 46.5% of the fabric weight, respectively.

Under similar conditions, using a mixture of equal parts of ethyl alcohol and 2-ethylhexyl 75 methacrylate, the temperature of this mixture in the same time is 6% of the fabric weight.

Under similar conditions, using a mixtureof equal parts of methyl methacrylate andZ-ethylhexyl methacrylate, the temperature of this mixture being 50 C., the amount of polymer deposited in the same time is 42% of the fabric weight.

Example 7 The recipe of Example. is used to form n.- butyl methacrylate polymer on a cotton fabric, the temperature of the monomer being 50 C. The amount of polymer formed on the fabric in 30 minutes is 4% of the fabric weight, when the rate of flow of carbon dioxide is 4.3 gms./sq. cm. of fabric/hr.

When the treatment is repeated, including the step of impregnating the fabric with the solution of ammonium persulphate, the total amount of polymer deposited is 54% of the weight of fabric,

being 50 C., the amount of polymer deposited I and, by a third treatment, this is increased to 150%. If the step of impregnating with ammonium persulphate solution is omitted in the second and third treatments, then the total amount of polymer deposited in three treatments is only 6%.

Example 8 time is 45% of the fabric weight.

Example 9 The recipe of Example 5 is used to form styrene polymer on absorbent paper, the temperature of the monomer being 50 C., andthe rate of flow of carbon dioxide being 4.3 gms./ sq. cm.

of fabric/hr. After treatment for 30 minutes, the paper gains in weight by only 2%, but after impregnating the paper again with the persula phate solution and treating for a further 30 minutes, the total gain in weight ls 24.5%. After a third treatment, the amount of polymer deposited corresponds to a total increase in weight Example 10 The recipe .of Example 5 is used topolymerise polymeric material formed on the fabric in 30.

minutes is 10% of the fabric weight.

We claim:

1. A process for treating fibrous material which comprises applying to said material an aqueous solution of a member of the class consisting of persulfuric acid and water soluble persulfates, exposing said material while moist with water to the vapor of a readily polymerizable compound containing the group CH2=CZ in the further presenceof a member of the-class consisting of water soluble oxy-acids of sulfur with reducing properties and water soluble salts of oxyacids of sulfur with reducing properties and simultaneously polymerizing said polymerizable compound on said material during the exposure of said material to said vapor.

2. The process of claim 1 wherein the .monomeric, readily polymerizable compound is an ester of an acrylic acid, the hydrocarbon group component of the ester containing not in excess of six carbon atoms.

3. The process of claim 1 wherein the monomeric, readily polymerizable compound has a high vapor. pressure at temperatures below 0.

4. The process of claim 1 wherein the persulfuric compound is ammonium persulfate.

5. The process of claim 1 wherein the sulfur compound is a sodium salt.

6. The process of claim 1 wherein the sulfur compound is sulfurous acid. i

'7. The process of claim 1 wherein the sulfur compoundis introduced in admixture with water vapor by entrainment with the vapor of the monomer in a carrier gas.

8. The process of claim lewherein the sulfurcompound is formed by introducing sulfur dioxide in admixture with a carrier gas.

WILLIAM CHARLTON. STANLEY GRAHAM JARRE'I'IH ERIC EVERARD WALKER. 

